1. Field of the Invention
The present invention relates to a recording medium having a data structure for managing reproduction of at least multiple audio streams recorded thereon as well as methods and apparatuses for reproduction and recording.
2. Description of the Related Art
An optical disc such as a DVD (Digital Versatile Disc), capable of recording high quality video and audio data for many hours, is being developed and released to consumer markets. Various types of DVD exist including DVD-ROM and DVD-RW (DVD-Rewritable).
Video and audio streams in a DVD-ROM are recorded in units of a program stream packet defined by the MPEG standard. As shown in FIG. 1, one pack corresponds to a single physical sector with the record size of 2048 bytes.
A single pack is composed of a pack header and includes packets of video, audio, and sub-pictures. The pack header includes pack start code (Pack_start_code), SCR, program mux rate (program_mux_rate), and stuffing length (Stuffing_length).
In a DVD-ROM where a single physical sector corresponds to a single pack in the above-described manner, multiple audio streams may be recorded in a number of respective coding formats in a data area of the DVD-ROM.
For example, as shown in FIG. 2, an audio pack where audio data are recorded according to LPCM (Linear Pulse Code Modulation) format comprises a pack header (Pack_header) of 14 bytes, a packet header (Packet_header) of more than one byte, sub-stream ID (sub_stream_id) of one byte, audio frame information (Audio_frame_information), audio data information (Audio_data_information), and PCM audio data ranging from one byte to 2013 bytes.
As shown in FIG. 3, in case of an audio pack where audio data are recorded according to Dolby AC-3 format, the audio pack comprises a pack header (Pack_header) of 14 bytes, a packet header (Packet_header) of more than one byte, audio frame information (Audio_frame_information), sub-stream ID (sub_stream_id) of one byte, audio frame information (Audio_frame_information), and Dolby AC-3 audio data ranging from one byte to 2016 bytes.
As described above, an audio pack which includes audio data recorded according to a particular coding format is recorded with a characteristic sub-stream ID (sub_stream_ID) so as to determine the coding format. At the same time, attribute information corresponding to the sub-stream ID is recorded and managed in the DVD-ROM as navigation information.
For example, as shown in FIG. 4, among navigation information recorded and managed in the DVD-ROM, VTS_AST_ATR (Video Title Set Audio Stream Attribute) information is included and recorded in a VTSI (Video Title Set Information) area. The VTS_AST_ATR includes eight VTS_AST_ATRs, namely, VTS_AST_ATRs of audio streams #0 ˜#7, corresponding to the respective sub-stream IDs.
The attribute information, as shown in FIG. 5, includes audio coding mode information, and the audio coding mode information includes information to identify the coding format of the audio data recorded in the corresponding audio pack.
For example, when the audio coding information corresponds to ‘000b’, it indicates that the corresponding audio data have been encoded according to Dolby AC-3 format. Audio coding information of ‘010b’ denotes encoding according to the MPEG-1 or MPEG-2 format without an extension bitstream, while ‘011b’ denotes that the corresponding audio data have been encoded according to the MPEG-1 or MPEG-2 format with an extension bitstream. In addition, audio coding mode information of ‘100b’ indicates that the corresponding audio data have been encoded according to LPCM format. An optical disc apparatus such as a DVD-player, when reading out audio data recorded in the DVD-ROM, refers to a characteristic sub-stream ID included in an audio pack and on this basis selects the audio stream requested for playback by the user.
Subsequently, the optical disc apparatus checks the audio coding mode information corresponding to the sub-stream ID of the selected audio stream and decodes the selected audio stream according to the coding format designated by the audio coding mode information. Therefore, the optical disc apparatus can normally perform selective play of an arbitrary audio stream requested by the user.
Recently, standardization of high-density optical discs such as a read-only Blu-ray disc (BD-ROM), which has a higher recording capacity than a DVD, is underway. However, an appropriate method for managing multiple audio streams for the high-density optical disc has not been established.